0b7b5cc1b3
Added option 'aria-pagecache-segments', default 1.
For values > 1, this split the aria-pagecache-buffer into the given
number of segments, each independent from each other. Having multiple
pagecaches improve performance when multiple connections runs queries
concurrently using different tables.
Each pagecache will use aria-pageache-buffer/segments amount of
memory, however at least 128K.
Each opened table has its index and data file use the segments in a
a round-robin fashion.
Internal changes:
- All programs allocating the maria pagecache themselves should now
call multi_init_pagecache() instead of init_pagecache().
- pagecache statistics is now stored in 'pagecache_stats' instead of
maria_pagecache. One must call multi_update_pagecache_stats() to
update the statistics.
- Added into PAGECACHE_FILE a pointer to files pagecache. This was
done to ensure that index and data file are using the same
pagecache and simplified the checkpoint code.
I kept pagecache in TABLE_SHARE to minimize the changes.
- really_execute_checkpoint() was update to handle a dynamic number of
pagecaches.
- pagecache_collect_changed_blocks_with_lsn() was slight changed to
allow it to be called for each pagecache.
- undefined not used functions maria_assign_pagecache() and
maria_change_pagecache()
- ma_pagecaches.c is totally rewritten. It now contains all
multi_pagecache functions.
Errors found be QA that are fixed:
MDEV-36872 UBSAN errors in ma_checkpoint.c
MDEV-36874 Behavior upon too small aria_pagecache_buffer_size in case of
multiple segments is not very user-friendly
MDEV-36914 ma_checkpoint.c(285,9): conversion from '__int64' to 'uint'
treated as an error
MDEV-36912 sys_vars.sysvars_server_embedded and
sys_vars.sysvars_server_notembedded fail on x86
Code status:
ci.appveyor.com
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